US Patent 7755115 - Multiwall CNTFET

http://www.freepatentsonline.com/7755115.html

Multiwall nanotubes are normally not able to form the channels of field effect transistors since they have metallic rather than semiconductive properties. However, this patent from Fujitsu teaches a way to remove a portion of the outer walls of a multiwall nanotube to form the semiconductor channel while using the two nanotube ends as conductive contacts to electrodes. Claim 1 reads:

1. A field effect transistor, comprising:

a carbon nanotube of two or more walls having an inner wall and an outer wall;

source and drain electrodes formed on both sides of the carbon nanotube; and

a gate electrode formed in a gate formation region of the carbon nanotube,

wherein the outer wall of the carbon nanotube is removed in the gate formation region to expose the inner wall, the gate electrode is formed over the exposed inner wall, and the carbon nanotube between the source and drain electrodes and the gate electrode is covered by the outer wall.